1. Technical Field
The invention relates to a planar light source. Particularly, the invention relates to a backlight module.
2. Related Art
Along with development of display technique, flat displays gradually replace conventional cathode ray tube (CRT) displays and become popular in display market. In the flat displays, liquid crystal displays (LCDs) are most popular and widely used. A general LCD is mainly composed of a backlight module and a liquid crystal panel. Since the liquid crystal panel is non-luminous itself, the backlight module is used to provide a light source for displaying.
Generally, the conventional backlight modules are grouped into direct type backlight modules and edge type backlight modules. Taking the edge type backlight module as an example, a light beam provided by a light source disposed at a light incident surface of a light guide plate is transmitted in internal of the light guide plate, and an optical microstructure (for example, an etching pattern or a screen printing pattern) at bottom of the light guide plate may spoil a total reflection of the light beam and guide the light beam to emit from a light emitting surface of the light guide plate, so as to form a planar light source.
U.S. Pat. No. 6,834,973 discloses a light guide plate having micro reflection structures on a bottom surface. Taiwan Patent No. 546520 discloses a light guide plate having wedge-shaped reflection grooves. Taiwan Patent No. 1282021 discloses a light guide plate, in which a microstructure has an arc-shaped reflection surface, and a shape of the microstructure is an arc quadrilateral or a fan viewed from a light emitting surface. Taiwan Patent No. 1222533 discloses a prism sheet having concave and convex patterns. U.S. Patent publication No. 20110241573 discloses a light guide plate having a plurality of groove groups, where each of the groove groups includes a plurality of bending grooves. Taiwan Patent publication No. 201213970 discloses a light guide plate, where a light reflection surface of the light guide plate has light guide microstructures and protruding microstructures. Taiwan Patent No. M321111 discloses a situation that microstructures are recessed into or protruded out from a bottom surface of the light guide plate. Taiwan Patent publication No. 200428044 discloses a method for manufacturing a light guide plate. Taiwan Patent No. 1292845 discloses a method for manufacturing a light guide plate mold core.